GH ACTION--REGULATION OF IGF-I GENE TRANSCRIPTION

生长激素（GH）和胰岛素样生长因子（IGF-I）都是 对脊椎动物的生长和分化至关重要。 GH是IGF-I产生的主要调节因子， 通过激活IGF-I基因转录。对机制进行定性 负责这种转录激活的人应该提供新的 药物设计的分子靶点，并最终导致更好的 代谢和生长障碍的治疗。 本实验室 在大鼠IGF-I基因中鉴定了一个染色质区域，称为HS 7， 经历GH调节的结构改变， 转录诱导的转录调控。 这个的目标 项目是表征介导的分子机制 通过评估HS 7在GH激活IGF-I基因中的作用， 转录调控 第一组实验将检验HS 7 介导GH诱导的IGF-I基因转录刺激。 几 将用GH转染已知表达IGF-I的细胞系 受体和各种报告基因融合到IGF-I或 具有或不具有HS 7位点的异源启动子。 一套平行 实验将描述核蛋白的特征， 在HS 7位点的IGF-I。 体外凝胶位移测定和足 印刷实验将与特定地点的 诱变以鉴定必需的特定核苷酸 并且足以用于高亲和力蛋白结合。几 将采用实验方法来鉴定和克隆 与HS 7相互作用的核蛋白。 一系列实验 将检验克隆蛋白质是特异性的假设， GH调节IGF-I基因转录的介质。

Growth (GH) and insulin-like growth factor (IGF-I) are both critically important for growth and differentiation in vertebrates. GH is the principal regulator of IGF-I production and acts primarily by activating IGF-I gene transcription. Characterizing the mechanisms responsible for this transcriptional activation should provide new molecular targets for drug design and ultimately lead to better treatment of metabolic and growth disorders. Our laboratory has identified a chromatin region in the rat IGF-I gene termed HS7 that undergoes GH-regulated structural alteration in parallel with hormone-induced transcriptional regulation. The goals of this project are to characterize the molecular mechanisms that mediate activation of IGF-I gene by GH by evaluating the role of HS7 in transcriptional control. The first set of experiments will test the hypothesis that HS7 mediates GH-induced stimulation of IGF-I gene transcription. Several cell lines known to express IGF-I will be transfected with GH receptor and various reporter genes fused to the IGF-I or heterologous promoters with or without the HS7 site. A parallel set of experiments will characterize the nuclear proteins that bind to the IGF-I at the HS7 site. In vitro gel shift assays and foot printing experiments will be used in conjunction with site-specific mutagenesis to identify the specific nucleotides that are necessary and sufficient for high affinity protein binding. Several experimental approaches will be employed to identify and clone the nuclear proteins that interact with HS7. A series of experiments will test the hypothesis that the cloned proteins are specific mediators of GH-regulated IGF-I gene transcription.